1. Field of the Invention
This invention relates to transmission of digital information over a communications network. More particularly, this invention relates to characterization of traffic flows in a packet switched network.
2. Description of the Related Art
The meanings of certain acronyms and abbreviations used herein are given in Table 1.
TABLE 1Acronyms and AbbreviationsNICNetwork Interface ControllerQoSQuality of ServiceTORTop of RackTCPTransmission Control ProtocolRDMARemote Direct Memory Access
A packet switched network may process different types of flows, which can be characterized as elephant flows and mouse flows. An elephant flow represents a long-lived flow or a continuous traffic flow that is typically associated with high volume connection. A mouse flow represents a short-lived flow. Mice flows are often associated with bursty, latency-sensitive applications, whereas elephant flows tend to be associated with large data transfers in which throughput over a sustained period of time is more important than latency.
Elephant flows tend to fill network buffers, which produces a queuing delay to anything that shares such buffers, in particular mouse flows. Mouse flows should generally receive high priority in order to comply with quality-of-service (QoS) requirements. Detection of elephant flows, is useful, not only for discrimination from mouse flows, but also for load-balancing and for network analysis generally.
There are many proposals for identifying elephant flows. For example, U.S. Patent Application Publication No. 2015/0124825 proposes tracking data flows and identifying large-data flows by extracting fields from a packet of data to construct a flow key, computing a hash value on the flow key to provide a hashed flow signature, entering and/or comparing the hashed flow signature with entries in a flow hash table. Each hash table entry includes a byte count for a respective flow. When the byte count for a flow exceeds a threshold value, the flow is added to a large-data flow table and the flow is then tracked in the large-data flow table.
U.S. Patent Application Publication No. 2017/0118090 proposes a forwarding element that inspects the size of each of several packets in a data flow to determine whether the data flow is an elephant flow. When the forwarding element receives a packet in a data flow, the forwarding element identifies the size of the packet. The forwarding element then determines if the size of the packet is greater than a threshold size. If the size is greater, the forwarding element specifies that the packet's data flow is an elephant flow.